Ocean Circulation Model Applications for the Estuary-Coastal-Open Sea Continuum

Abstract

Coastal zones are among the most variable environments. As such, they require adaptive water management to ensure the balance of economic and social interests with environmental concerns. High quality marine data of hydrographic conditions e.g., sea level, temperature, salinity, and currents are needed to provide a sound foundation for the decision making process. Operational models with sufficiently high forecasting quality and resolution can be used for a further extension of the marine service toward the coastal-estuary areas. The Limfjord is a large and shallow water body in Northern Jutland, connecting the North Sea in the West and the Kattegat in the East. It is currently not covered by the CMEMS service, despite its importance for sea shipping, aquaculture and mussel fisheries. In this study, we use the operational HIROMB-BOOS Model (HBM) to resolve the full Baltic-Limfjord-North Sea system with a horizontal resolution of 185.2 m in the Limfjord. The study shows several factors that are essential for successfully modeling the coastal-estuary system: (a) high computational efficiency and flexible grids to allow high resolution in the fjord, (b) an improved short wave radiation scheme to model the thermodynamics and the diurnal variability of the temperature in very shallow waters, (c) high resolution atmospheric forcing, (d) adequate river forcing, and (e) accurate bathymetry in the narrow straits. With properly resolving these issues, the system is able to provide high quality sea level forecast for storm surge warning and hydrography forecasts: temperature, salinity and currents with sufficiently good quality for ecosystem-based management. The model is able to simulate the complex spatial and temporal pattern of sea level, salinity and temperature in the Limfjord and to reproduce their diurnal, seasonal and interannual variability and stratification rather well. Its high computational efficiency makes it possible to model the transition from the basin-scales to coastal- and estuary-scales seamlessly. In total, The HBM model has been successfully extended, to include the complex estuary system of the Limfjord, and shows an adequate model performance with regards to sea level, salinity and temperature predictions, suitable for storm surge warning applications and coastal management applications.

Transport of Microplastics From the Daugava Estuary to the Open Sea

“…The oceanographic model on the transport of MPs is built based on the HBM which enables a seamless transition from ocean to estuary scales by using the dynamic two-way nesting (Murawski et al, 2021;Frishfelds et al, 2021) and the HBM-based MP dynamic module (Murawski et al, 2022), which includes three two-way nested domains, hereafter referred to as the threedomain model:…”

“…HBM is a three-dimensional, free-surface, baroclinic ocean circulation model (Frishfelds et al, 2021;Murawski et al, 2021). The model code is efficient and highly parallelized both with OpenMP and MPI interfaces (Berg and Poulsen, 2012).…”

“…The case with the standalone setup had the lowest correlation as it lacked two-way nesting with the Gulf of Riga despite having a higher resolution. The standalone setup did not describe momentary currents correctly at the boundaries (Frishfelds et al, 2021;Murawski et al, 2021). Therefore, proper boundary conditions can be more essential than the resolution of a coastal model, especially when estimating transport from inland waters to open seas.…”

“…The recent development in seamless modeling has enabled a modeling capacity to resolve the LOAC system with flexible model grids (She and Murawski, 2018;Frishfelds et al, 2021;Murawski et al, 2022). For example, a 3D hydrodynamic model, the HIROMB-BOOS model (HBM), has been applied to riverine-estuarial-coastal-open sea modeling with multiple two-way nested domains (Frishfelds et al, 2021;Murawski et al, 2021).…”

A Cross Disciplinary Framework for Cost-Benefit Optimization of Marine Litter Cleanup at Regional Scale

“…The HBM model is validated on annual basis as DMI's operational storm surge model. It has been extensively validated as CMEMS Baltic marine Forecasting model until 2020 (She, 2014) and as operational model for coastal applications (Murawski et al, 2021).…”